Continuous passive motion is used to reduce pain, help joint flexibility and generally reduce recovery time from many orthopedic operations, particularly of the knee and hip. A circular motion (circumduction) of the head of the femur relative to the acetabulum (pelvis) through a prescribed range without muscle contractions provides for desirable continuous passive motion of a hip joint. Other passive motions (e.g. extension, flexion, abduction, adduction, internal rotation, external rotation) of the femur relative to the acetabulum may prove to be beneficial as more research and clinical data is collected. Physical or occupational therapists or nurses perform circumduction of the hip joint by manual manipulation. The size of the patient can make the manual technique difficult to perform and/or maintain for an extended period of time. Circumduction currently performed by a therapist or nurse is generally only sustainable for 10-30 minutes each session. More often than not, patients are only able to receive a maximum of one session per day during extended out-patient recovery. Current clinical data suggests, however, that at least two hours of continuous passive motion (circumduction) of the hip joint is required for maximum benefit, and shorter recovery and rehabilitation times.
There are presently continuous passive motion machines designed to be used for therapeutic treatment of the knee, ankle, wrist, and shoulder. Because of the benefits of prolonged mechanized continuous passive motion, current therapies for the hip joint often use a machine designed for the knee. A machine designed for the knee does not confer the maximum targeted benefit for a hip joint. The knee device for instance performs flexion and extension of the leg and femur relative to the pelvis. Flexion and extension of the leg, while somewhat beneficial to recovery of the hip joint, does not confer the identical benefits to the hip joint as circumduction.